Fuel supply lines are attached to fuel system components of a gas turbine by fittings. The fittings each include a sealing arrangement that utilizes metal to metal contact in order to inhibit the leakage of fuel from the fitting. Referring to FIG. 1, a type of fitting that is frequently used includes a projecting cone portion 10 having a clearance surface 12 located between first 14 and second 16 cone sealing surfaces. The first 14 and second 16 sealing surfaces each taper toward a connection end 18 of the cone portion 10. The taper of the first sealing surface 14 is substantially identical to the taper of the second sealing surface 16.
In use, the cone portion 10 is received by a receptacle portion of the fitting. The receptacle portion includes a cavity having a tapered receptacle sealing surface which corresponds to the taper of the first 14 and second 16 sealing surfaces. When a fuel supply line is attached to a fuel system component, the first 14 and second 16 sealing surfaces come in contact with the receptacle sealing surface and form a seal. It is noted that the clearance surface 12 is located beneath the plane of first 14 and second 16 sealing surfaces. Thus, the clearance surface 12 does not contact the receptacle sealing surface and does not provide any sealing functionality.
Sections of the first 14 and/or second 16 sealing surfaces and/or clearance surface 12 may become damaged as a result of accidental contact with another component or equipment. For example, this may occur if the fuel line is accidentally dropped by an operator during assembly operations. In particular, FIG. 1 depicts damage in the form of an exemplary first 20 and second 21 gouges formed on the first sealing surface 14 and the clearance surface 12, respectively.
Referring to FIG. 2, a cross sectional view of the first sealing surface 14, a receptacle sealing surface 22 and gouge 20 is shown. Formation of the gouge 20 typically results in material from the first sealing surface 14 being displaced and reshaped into raised bulges 24. The bulges 24 cause misalignment between the first sealing surface 14 and the receptacle sealing surface 22 in the area of the bulges 24, thus resulting in a compromised seal and the possibility of fuel leaks.
A damaged portion of a fitting, such as cone portion 10, is replaced by cutting the cone portion 10 from the fuel line and welding a new cone portion 10 in its place. The weld then undergoes an x-ray inspection procedure to verify that welding requirements are met. However, welding requires a qualified welder and a hot work permit. In addition, performing an x-ray inspection requires a certified technician and the clearance of personnel from the work area in order to prevent exposure to x-rays. Further, there is a long wait time in obtaining replacement fittings. As such, the current process for replacing a damaged fitting is expensive and time consuming.